As methods of preparing polymeric resin fine particles (resin fine particles) industrially via an emulsion polymerization method or a suspension polymerization method, known are methods of preparing those employing a batch type reactor or a continuous type reactor.
The batch reactor produced problems such as large non-production time which is not related to a polymerization reaction, increased initial plant investment for a large sized reactor; and an increasing amount of energy consumption to make up for heat transfer capacity.
On the other hand, it is advantageous in a continuous type reactor that non-production time can be largely reduced, and the apparatus is possible to be reduced in size, and it is employed by taking advantage of this merit.
A continuous type reactor is mainly a reactor such as a tank type reactor or a tube type reactor. Since a tabular flow-feeding apparatus as a continuous type reactor of the two has a simple structure, and makes a suppressed residence time distribution to be small, it has been used for preparation of a polymeric resin material as many cases desired for the reaction system showing small variations in the reaction conditions such as a temperature distribution, a stirring speed and so forth (refer to Patent Documents 1-3, for example).
Specifically, in the foregoing Patent Document 1, disclosed is a technique in which an inner diameter of a reactor tube constituting a tube type reactor used for a polymerization apparatus to prepare toner via a polymerization method, and a circulation line speed and properties of a polymerizable monomer composition dispersion are specified. Further, in Patent Document 2, disclosed is a technique in which a fluoropolymer is prepared with a tube type polymerization reactor by specifying a cross-section of a channel. Further, in Patent Document 3, disclosed is a technique in which a (meth) acrylic acid ester-styrene copolymer for an optical member is manufactured with a polymerization apparatus equipped with a plug flow type reactor.
However, as one of methods to obtain polymeric resin fine particles exhibiting a sharp particle size distribution and a narrow molecular weight distribution, there is a method of conducting polymerization reaction in a state where a plug flow property is acquired. “Plug flow property” also called “pressed flow property” is that the polymerization reaction is accelerated in a polymerizable monomer composition dispersion moving inside a reactor to form resins, and the moving dispersion is controlled in such a way that a concentration distribution of the composition is maintained in an even state. That is, the dispersion of the polymerizable monomer composition is fed to the reactor after splitting ir, and the monomer dispersion having been split is moving at constant speed in the reactor. In this case, the rate of mixture as well as diffusion in the moving direction of the monomer dispersion is negligibly small, and the concentration distribution of the dispersion in the direction perpendicular to the moving direction has substantially become even.
As a specific method to obtain a plug flow property, for example, provided is a method of making a ratio (relationship) (La/D) to be large (for example, exceeding 100), wherein the ratio is a ratio of length (La) of a cylindrical channel to inner diameter (D) of the cylindrical channel, but in such a case, difficulty in downsizing of the tubular flow reactor results. In the above-described Patent Document, any of the literatures has disclosed a tube type reactor fitted with a plug flow property, but no description indicating a technique by which a reactor is downsized has been seen.
Patent Document 1: Japanese Patent O.P.I. (Open to Public Inspection) Publication No. 2003-140386
Patent Document 2: Japanese Patent O.P.I. Publication No. 2004-250627
Patent Document 3: Japanese Patent O.P.I. Publication No. 2008-291250